Low pressure drop static mixing system

ABSTRACT

A contaminated gas stream can be passed through an in-line mixing device, positioned in a duct containing the contaminated gas stream, to form a turbulent contaminated gas stream. One or more of the following is true: (a) a width of the in-line mixing device is no more than about 75% of a width of the duct at the position of the in-line mixing device; (b) a height of the in-line mixing device is no more than about 75% of a height of the duct at the position of the in-line mixing device; and (c) a cross-sectional area of the mixing device normal to a direction of gas flow is no more than about 75% of a cross-sectional area of the duct at the position of the in-line mixing device. An additive can be introduced into the contaminated gas stream to cause the removal of the contaminant by a particulate control device.

REFERENCE TO RELATED APPLICATION

The present application claims the benefit of U.S. ProvisionalApplication Ser. No. 62/084,413, filed Nov. 25, 2014, which isincorporated herein by this reference in its entirety.

Cross reference is made to U.S. patent application Ser. No. 13/951,167,filed Jul. 25, 2013, entitled “PROCESS TO ENHANCE MIXING OF DRY SORBENTSAND FLUE GAS FOR AIR POLLUTION CONTROL” (now U.S. Pat. No. 8,974,756),which is incorporated herein by this reference in its entirety.

FIELD

The disclosure relates generally to treatment of waste gas andparticularly to applying additives to waste gas to remove targetcontaminants.

BACKGROUND

Increasingly stringent pollution control standards for acid gases andtrace air toxics, including hydrochloric acid (HCl), sulfur trioxide(SO₃), and mercury (Hg), pose greater challenges for industries. Currentbest control practices for sorbent pollution control processes, such asactivated carbon injection (ACI) and dry sorbent injection (DSI), mustbe improved. In many cases, a further increase in sorbent injection rateis uneconomical, ineffective, and/or otherwise adversely impacts thewaste gas treatment process.

External constraints can also hamper additive or sorbent performance.The effectiveness of in-duct sorbent injection can often be limited dueto constraints of duct layout, non-ideal injection locations, sorbentin-flight residence time, temperature, adverse flue gas chemistry, andclose proximity to particulate control device.

Devices placed in the duct to improve additive or sorbent performance,such as in-line gas mixing devices, can cause operational issues. Atperiods of high load, for example when a power plant is running at ornear full capacity during summer extremes, the pressure drop caused bycan cause a measurable impact on plant performance and efficiency.

There is therefore a need for improved methods of sorbent/gas mixingthat can be implemented in limited duct space while maintaining plantoperational parameters within acceptable levels.

There is a further need for methods and systems that can achieve desiredsorbent/gas mixing with lower pressure drop at high or peak loadconditions.

SUMMARY

These and other needs are addressed by the various aspects, embodiments,and configurations of the present disclosure. The disclosure is directedto a method and system for enhanced removal of contaminants from coalcombustion and other thermal processes, particularly the use of variousmixing device configurations that can provide improved additivedistribution in a contaminated gas stream and/or can reduce the pressuredrop across a mixing device.

The method and system can include:

(a) a thermal unit to heat (e.g., combust) a contaminated feed materialand produce a contaminated gas stream;

(b) an optional air heater to transfer thermal energy from thecontaminated gas stream to air prior to introduction of the air into thethermal unit;

(c) a mixing device (typically a static mixing device) to induceturbulent flow in the contaminated gas stream;

(d) an additive injection system, positioned downstream of the mixingdevice, to introduce an additive into the contaminated gas stream, theadditive controlling a contaminate level in a treated gas stream (e.g.,at least partially removing or causing the removal of the contaminant)prior to discharge of the treated gas stream into the environment;

(e) the mixing device positioned downstream of the additive injectionsystem to form a mixed gas stream comprising a typically substantiallyhomogeneous distribution of the additive in the mixed gas stream; and

(f) a downstream particulate control device to remove particulates(which can include the contaminant and/or a derivative thereof) from theadditive-containing gas stream and from the treated gas stream.

The additive-containing gas stream can include a substantiallyhomogeneous distribution of the additive in the additive-containing gasstream.

The energy for mixing by the mixing device can be primarily from a lossin pressure as the contaminated gas stream flows through the mixingdevice.

The contaminant can include mercury, and the additive can be one or moreof a halogen, halide, and powdered activated carbon.

The contaminant can include one or more of nitrogen oxides (NO_(X)),sulfur oxides (SOx), hydrochloric acid (HCl), hydrogen sulfide, andhydrofluoric acid (HF), and the additive one or more of lime, analkaline earth metal sesquicarbonate, an alkali metal sesquicarbonate, ametal oxide, an alkaline earth metal carbonate, an alkali earth metalcarbonate, an alkaline earth metal bicarbonate, and an alkali earthmetal bicarbonate.

In the additive-containing gas stream, the distance from an output ofthe mixing device to an input of a downstream particulate control devicecan be at least about one times the hydraulic diameter of the pipe orduct, but is commonly no more than about ten times the hydraulicdiameter.

The distance from a point of introduction of the additive into thecontaminated gas stream to an input to the mixing device can be at leastabout one times the hydraulic diameter but is commonly no more thanabout ten times the hydraulic diameter.

A distance from an output of the static mixing device to a location ofintroduction of the additive (or in some applications from a point ofintroduction of the additive into the contaminated gas stream to aninput to the mixing device) can be no more than about one times thehydraulic diameter of a conduit positioned between the mixing device andintroduction location.

The mixing device can be a static mixing device having an arrangement ofmixing elements in one or more mixing sections. The mixing elements, forinstance, can be one or more of static fan-type blades, baffles, and/orplates. The mixing elements can be curved and/or helically shaped. Thearrangement of mixing elements commonly includes from about 1 to about 5static, or substantially stationary and/or fixed, mixing elements butcan include from about 2 to about 25 mixing elements.

The flue gas velocity of the contaminated gas stream commonly rangesfrom about 5 to about 50 m/s.

The additive-containing gas stream can have substantially turbulentflow, and the mixing device can simultaneously cause flow division andradial mixing in the additive-containing gas stream.

A number of differing process configurations are possible.

The additive, whether an acid gas controlling, mercury capture additive,flue gas conditioning agent, or other additive, may be added downstreamof the mixing device or mixing system.

The additive, whether an acid gas controlling or mercury captureadditive, can be introduced into the contaminated gas stream downstreamof an air heater, and the mixing device can be positioned downstream ofboth the air heater and the point of introduction of the additive.

The acid gas controlling additive can be an alkaline sorbent, and thealkaline sorbent and/or a mercury capture sorbent can be introduced intothe contaminated gas stream downstream of the mixing device.

The alkaline sorbent can be introduced into the contaminated gas streamdownstream of a first particulate control device and upstream of asecond particulate control device.

The additive can be introduced into the contaminated gas stream upstreamof an air heater.

The static mixing device can be positioned upstream of the air heater.

The additive can be an alkaline sorbent, and the alkaline sorbent and/ora mercury capture sorbent can be introduced into the contaminated gasstream downstream of the mixing device and air heater.

The mixing device can be positioned downstream of the air heater.

The additive can be an alkaline sorbent, and the alkaline sorbent and/ora mercury capture sorbent can be introduced into the contaminated gasstream downstream of the mixing device and air heater.

The additive can include both an alkaline sorbent and a mercury capturesorbent, and both the alkaline and mercury capture sorbents can beintroduced into the contaminated gas stream upstream of the mixingdevice.

A mixing system can comprise a plurality of mixing devices. Theplurality of mixing devices may be organized in an array. Typically, thearray contains rows and columns. Rows or columns of mixing devices in anarray may be rotated about an axis. Such rotation may reduce theoperational cross sectional area (or cross-sectional area of the mixingdevice normal to the direction of gas flow) of the mixing devicesrelative to the cross sectional area of the pipe or duct (normal to thedirection of gas flow).

An array of mixing devices can comprise rotatable mixing elements. Themixing elements may be adjusted individually, or they may be part of arotating axis that runs through a row or column of mixing devices.

A method and system can include:

a thermal unit to heat (e.g., combust) a contaminated feed material andproduce a contaminated gas stream;

an optional air heater to transfer thermal energy from the contaminatedgas stream to air prior to introduction of the air into the thermalunit;

an in-line mixing device to induce turbulent flow in the contaminatedgas stream, with one or more of the following being true:

-   -   (a) a width of the in-line mixing device is no more than about        75% of a width of the duct at the position of the in-line mixing        device;    -   (b) a height of the in-line mixing device is no more than about        75% of a height of the duct at the position of the in-line        mixing device; and    -   (c) a cross-sectional area of the mixing device normal to a        direction of gas flow is no more than about 75% of a        cross-sectional area of the duct at the position of the in-line        mixing device;

an additive injection system, positioned upstream or downstream of thein-line mixing device, to introduce an additive (e.g., a solid, liquid,or gas) into the contaminated gas stream, the additive controlling acontaminate level in a treated gas stream prior to discharge of thetreated gas stream into the environment, the additive-containing gasstream comprising a substantially homogeneous distribution of theadditive in the additive-containing gas stream; and

a downstream particulate control device to remove particulates from theadditive-containing gas stream and form the treated gas stream.

The in-line mixing device can be a static or dynamic mixing device andcan cover only part of the cross section of a duct or pipe. For example,the mixing device can cover less than 50%, or less than 25%, of thecross section of the duct.

When the additive is injected downstream of the mixing device, themixing device can create a turbulent zone that induces mixing of theadditive in the gas stream even though the mixing device covers onlypart of the duct.

A gas treatment system and method can include:

a thermal unit to heat (e.g., combust) a contaminated feed material andproduce a contaminated gas stream; and

a mixing device positioned in a conduit for transporting thecontaminated gas stream, wherein, in a first operating mode, the mixingdevice and/or a member thereof has a first position relative to adirection of flow of the contaminated gas stream and, in a secondoperating mode, the mixing device and/or a member thereof has adifferent second position relative to the direction of flow of thecontaminated gas stream.

One or more of the following can be true:

-   -   (a) the first operating mode provides a first pressure drop of        the contaminated gas stream passing the mixing device and the        second operating mode provides a second pressure drop of the        contaminated gas stream passing the mixing device, the first        pressure drop being greater than the second pressure drop;    -   (b) the first operating mode provides a first level of turbulent        flow of the contaminated gas stream passing the mixing device        and the second operating mode provides a second level of        turbulent flow of the contaminated gas stream passing the mixing        device, the first level of turbulent flow being greater than the        second level of turbulent flow;    -   (c) in the first operating mode, a plane of a face of the mixing        device has a first angular orientation relative to a direction        of flow of the contaminated gas stream and in the second        operating mode the plane of the face of the mixing device has a        second angular orientation relative to the direction of flow of        the contaminated gas stream, the first and second angular        orientations being different; and    -   (d) in the first operating mode and during a selected time        interval, a first amount of the contaminated gas stream passes        through the mixing device and, in the second operating mode and        during the selected time interval, a second amount of the        contaminated gas stream passes through the mixing device, the        first amount being greater than the second amount.

A computer-controlled feedback system can be utilized to determine whenthe mixing devices, or the mixing elements, should be moved from thefirst to the second orientations and vice versa.

The control system can include:

a microprocessor;

a computer readable medium coupled to the microprocessor;

a sensor to sense a stimulus; and

a mixing device positioned in a contaminated gas stream.

The microprocessor, in response to receiving a sensed stimulusindicating an occurrence of a selected event (e.g., a selected,determined, or predetermined current power load, pressure drop, sorbentconsumption, and/or sensed contaminant concentration), can change aposition and/or orientation of the mixing device and/or a member thereofrelative to a direction of flow of the contaminated gas stream from afirst position and/or orientation to a second position and/ororientation to change one or more of the above parameters (a)-(d) of thecontaminated gas stream passing the mixing device.

The computer-controlled feedback system may be connected to a mechanicalactuating system that rotates the static mixing devices or mixingelements.

The present disclosure can provide a number of advantages depending onthe particular configuration. The disclosed process and system cancouple a primary sorbent injection process with an upstream ordownstream stationary static gas mixing device having a high degree ofmixing effectiveness to achieve a more uniform particle distribution, toeliminate substantially stratification, such as from a verticaltemperature gradient, or cause destratification in the gas stream, andto improve contact between gas and sorbent. Typical applications aregas/gas mixing such as ammonia distribution in a Selective CatalyticReduction or SCR unit. However, in the method and system, the same orsimilar mixing device geometry can achieve substantially uniformparticle mixing with gas over a shorter, and often the shortestpossible, path. The substantially uniform particle mixing can enhancemass transfer of trace pollutants to the sorbent with a minimal impacton system pressure drop. The disclosed process and system can providereduced sized mixing devices to reduce pressure drop in the gas stream.The disclosed process and system can, for example, provide reducedpressure drop by alternating a position and/or orientation of the mixingdevice(s) relative to a direction of gas stream flow. The disclosedprocess and system can provide a control-feedback computational systemthat varies the pressure drop in response to one or more sensed stimuli.

These and other advantages will be apparent from the disclosure of theaspects, embodiments, and configurations contained herein.

“A” or “an” entity refers to one or more of that entity. As such, theterms “a” (or “an”), “one or more” and “at least one” can be usedinterchangeably herein. It is also to be noted that the terms“comprising”, “including”, and “having” can be used interchangeably.

“Absorption” is the incorporation of a substance in one state intoanother of a different state (e.g. liquids being absorbed by a solid orgases being absorbed by a liquid). Absorption is a physical or chemicalphenomenon or a process in which atoms, molecules, or ions enter somebulk phase—gas, liquid or solid material. This is a different processfrom adsorption, since molecules undergoing absorption are taken up bythe volume, not by the surface (as in the case for adsorption).

“Adsorption” is the adhesion of atoms, ions, biomolecules, or moleculesof gas, liquid, or dissolved solids to a surface. This process creates afilm of the adsorbate (the molecules or atoms being accumulated) on thesurface of the adsorbent. It differs from absorption, in which a fluidpermeates or is dissolved by a liquid or solid. Similar to surfacetension, adsorption is generally a consequence of surface energy. Theexact nature of the bonding depends on the details of the speciesinvolved, but the adsorption process is generally classified asphysisorption (characteristic of weak van der Waals forces) orchemisorption (characteristic of covalent bonding). It may also occurdue to electrostatic attraction.

“At least one”, “one or more”, and “and/or” are open-ended expressionsthat are both conjunctive and disjunctive in operation. For example,each of the expressions “at least one of A, B and C”, “at least one ofA, B, or C”, “one or more of A, B, and C”, “one or more of A, B, or C”and “A, B, and/or C” means A alone, B alone, C alone, A and B together,A and C together, B and C together, or A, B and C together. When eachone of A, B, and C in the above expressions refers to an element, suchas X, Y, and Z, or class of elements, such as X₁-X_(n), Y₁-Y_(m), andZ₁-Z_(o), the phrase is intended to refer to a single element selectedfrom X, Y, and Z, a combination of elements selected from the same class(e.g., X₁ and X₂) as well as a combination of elements selected from twoor more classes (e.g., Y₁ and Z_(o)).

The term “automatic” and variations thereof, as used herein, refers toany process or operation, which is typically continuous orsemi-continuous, done without material human input when the process oroperation is performed. However, a process or operation can beautomatic, even though performance of the process or operation usesmaterial or immaterial human input, if the input is received beforeperformance of the process or operation. Human input is deemed to bematerial if such input influences how the process or operation will beperformed. Human input that consents to the performance of the processor operation is not deemed to be “material”.

“Biomass” refers to biological matter from living or recently livingorganisms. Examples of biomass include, without limitation, wood, waste,(hydrogen) gas, seaweed, algae, and alcohol fuels. Biomass can be plantmatter grown to generate electricity or heat. Biomass also includes,without limitation, plant or animal matter used for production of fibersor chemicals. Biomass further includes, without limitation,biodegradable wastes that can be burnt as fuel but generally excludesorganic materials, such as fossil fuels, which have been transformed bygeologic processes into substances such as coal or petroleum. Industrialbiomass can be grown from numerous types of plants, includingmiscanthus, switchgrass, hemp, corn, poplar, willow, sorghum, sugarcane,and a variety of tree species, ranging from eucalyptus to oil palm (orpalm oil).

“Coal” refers to a combustible material formed from prehistoric plantlife. Coal includes, without limitation, peat, lignite, sub-bituminouscoal, bituminous coal, steam coal, waste coal, anthracite, and graphite.Chemically, coal is a macromolecular network comprised of groups ofpolynuclear aromatic rings, to which are attached subordinate ringsconnected by oxygen, sulfur, and aliphatic bridges.

The term “computer-readable medium” as used herein refers to anycomputer-readable storage and/or transmission medium that participate inproviding instructions to a processor for execution. Such acomputer-readable medium can be tangible, non-transitory, andnon-transient and take many forms, including but not limited to,non-volatile media, volatile media, and transmission media and includeswithout limitation random access memory (“RAM”), read only memory(“ROM”), and the like. Non-volatile media includes, for example, NVRAM,or magnetic or optical disks. Volatile media includes dynamic memory,such as main memory. Common forms of computer-readable media include,for example, a floppy disk (including without limitation a Bernoullicartridge, ZIP drive, and JAZ drive), a flexible disk, hard disk,magnetic tape or cassettes, or any other magnetic medium,magneto-optical medium, a digital video disk (such as CD-ROM), any otheroptical medium, punch cards, paper tape, any other physical medium withpatterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, a solidstate medium like a memory card, any other memory chip or cartridge, acarrier wave as described hereinafter, or any other medium from which acomputer can read. A digital file attachment to e-mail or otherself-contained information archive or set of archives is considered adistribution medium equivalent to a tangible storage medium. When thecomputer-readable media is configured as a database, it is to beunderstood that the database may be any type of database, such asrelational, hierarchical, object-oriented, and/or the like. Accordingly,the disclosure is considered to include a tangible storage medium ordistribution medium and prior art-recognized equivalents and successormedia, in which the software implementations of the present disclosureare stored. Computer-readable storage medium commonly excludes transientstorage media, particularly electrical, magnetic, electromagnetic,optical, magneto-optical signals.

A “computer readable storage medium” may be, for example, but notlimited to, an electronic, magnetic, optical, electromagnetic, infrared,or semiconductor system, apparatus, or device, or any suitablecombination of the foregoing. More specific examples (a non-exhaustivelist) of the computer readable storage medium would include thefollowing: an electrical connection having one or more wires, a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), an optical fiber, a portable compact disc read-onlymemory (CD-ROM), an optical storage device, a magnetic storage device,or any suitable combination of the foregoing. In the context of thisdocument, a computer readable storage medium may be any tangible mediumthat can contain, or store a program for use by or in connection with aninstruction execution system, apparatus, or device.

A computer readable signal medium may be any computer readable mediumthat is not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device. A computer readablesignal medium may convey a propagated data signal with computer readableprogram code embodied therein, for example, in baseband or as part of acarrier wave. Such a propagated signal may take any of a variety offorms, including, but not limited to, electro-magnetic, optical, or anysuitable combination thereof. Program code embodied on a computerreadable signal medium may be transmitted using any appropriate medium,including but not limited to wireless, wireline, optical fiber cable,RF, etc., or any suitable combination of the foregoing.

The terms “determine”, “calculate” and “compute,” and variationsthereof, as used herein, are used interchangeably and include any typeof methodology, process, mathematical operation or technique.

A “dynamic mixer” or “dynamic mixing device” is a device for thecontinuous or substantially continuous mixing of fluid materials.Dynamic mixers can be used to mix liquid and/or gas streams, dispersegas into liquid, or blend immiscible liquids. The energy needed formixing comes primarily from movement of mixing elements in the dynamicmixer. Typical construction materials for dynamic mixer componentsinclude stainless steel, polypropylene, Teflon™, polyvinylidene fluoride(“PVDF”), polyvinyl chloride (“PVC”), chlorinated polyvinyl chloride(“CPVC”) and polyacetal.

“High alkali coals” refer to coals having a total alkali (e.g., calcium)content of at least about 20 wt. % (dry basis of the ash), typicallyexpressed as CaO, while “low alkali coals” refer to coals having a totalalkali content of less than 20 wt. % and more typically less than about15 wt. % alkali (dry basis of the ash), typically expressed as CaO.

“High iron coals” refer to coals having a total iron content of at leastabout 10 wt. % (dry basis of the ash), typically expressed as Fe₂O₃,while “low iron coals” refer to coals having a total iron content ofless than about 10 wt. % (dry basis of the ash), typically expressed asFe₂O₃. As will be appreciated, iron and sulfur are typically present incoal in the form of ferrous or ferric carbonates and/or sulfides, suchas iron pyrite.

“High sulfur coals” refer to coals having a total sulfur content of atleast about 3 wt. % (dry basis of the coal) while “medium sulfur coals”refer to coals having between about 1.5 and 3 wt. % (dry basis of thecoal) and “low sulfur coals” refer to coals having a total sulfurcontent of less than about 1.5 wt. % (dry basis of the coal).

The “hydraulic diameter” is a commonly used term when handling flow innoncircular tubes and channels. The hydraulic diameter is defined asfour times the cross-sectional area of the channel divided by the insideperimeter of the channel.

“Laminar flow” (or streamline flow) occurs when a fluid flows insubstantially parallel layers, with little or no disruption between thelayers. At low flow velocities, the fluid tends to flow without lateralmixing, and adjacent layers slide past one another like playing cards.There are commonly no cross currents perpendicular to the direction offlow, nor eddies or swirls of fluids. In laminar flow, the motion of theparticles of fluid is very orderly with all particles moving in straightlines parallel to the pipe walls. In fluid dynamics, laminar flow is aflow regime characterized by high momentum diffusion and low momentumconvection. When a fluid is flowing through a closed channel such as apipe or between two flat plates, either of two types of flow may occurdepending on the velocity of the fluid: laminar flow or turbulent flow.Laminar flow tends to occur at lower velocities, below the onset ofturbulent flow.

“Lime” refers to a caustic alkaline earth metal substance, such ascalcium hydroxide (Ca(OH)₂), calcium oxide, and mixtures thereofproduced by heating limestone.

A “load profile” refers to a graph of the variation in the electricalload versus time. A load profile will generally vary according tocustomer type (typical examples include residential, commercial andindustrial), temperature and holiday seasons. Power producers use thisinformation to plan how much electricity they will need to makeavailable at any given time. Load profiles are typically determined bydirect metering and/or inferred from customer billing or other data. Ina load research calculation, a utility uses a transformer's maximumdemand reading and accounting for the known number of each customer typesupplied by the transformers. Actual demand can be collected atstrategic locations to perform more detailed load analysis, which can bebeneficial to both distribution and end-user customers looking for peakconsumption. Smart grid meters, utility meter load profilers, datalogging sub-meters and portable data loggers accomplish this task byrecording readings at a set interval.

“Particulate” refers to fine particles, such as fly ash, unburnedcarbon, contaminate-carrying powdered activated carbon, soot, byproductsof contaminant removal, excess solid additives, and other fine processsolids, typically entrained in a mercury-containing gas stream.

“Means” as used herein shall be given its broadest possibleinterpretation in accordance with 35 U.S.C., Section 112, Paragraph 6.Accordingly, a claim incorporating the term “means” shall cover allstructures, materials, or acts set forth herein, and all of theequivalents thereof. Further, the structures, materials or acts and theequivalents thereof shall include all those described in the summary ofthe disclosure, brief description of the drawings, detailed description,abstract, and claims themselves.

The term “module” as used herein refers to any known or later developedhardware, software, firmware, artificial intelligence, fuzzy logic, orcombination of hardware and software that is capable of performing thefunctionality associated with that element.

“Pressure drop” refers to the difference in pressure between two pointsof a fluid carrying network. Pressure drop occurs when frictionalforces, caused by the resistance to flow, act on a fluid as it flowsthrough the tube. Pressure drop is determined by measuring the absoluteor gauge pressure at the two points and determining the difference.Alternatively, differential pressure can be directly measured for thetwo points. Devices used to measure pressure include pressure gauges andmanometers. Examples of pressure gauges include hydrostatic pressuregauges, piston-type gauges, liquid columns (using the pressure headequation), McLeod gauges, aneroid gauges (e.g., Bourdon pressure gauges,diaphragm gauges, and bellows gauges), magnetic coupling gauges,spinning rotor gauges, electronic pressure sensors, thermal conductivitygauges, Pirani gauges, two-wire gauges, ionization gauges (e.g., hotcathode gauges and cold cathod gauges), and the like.

“Separating” and cognates thereof refer to setting apart, keeping apart,sorting, removing from a mixture or combination, or isolating. In thecontext of gas mixtures, separating can be done by many techniques,including electrostatic precipitators, baghouses, scrubbers, and heatexchange surfaces.

A “sorbent” is a material that sorbs another substance; that is, thematerial has the capacity or tendency to take it up by sorption.

“Sorb” and cognates thereof mean to take up a liquid or a gas bysorption.

“Sorption” and cognates thereof refer to adsorption and absorption,while desorption is the reverse of adsorption.

A “static mixer” or “static mixing device” is a device for thecontinuous or substantially continuous mixing of fluid materials. Staticmixers can be used to mix liquid and/or gas streams, disperse gas intoliquid, or blend immiscible liquids. The energy needed for mixing comesprimarily from a loss in pressure as fluids flow through the staticmixer. One common design of static mixer is the plate-type mixer.Another common design includes mixer elements contained in a cylindrical(tube) or squared housing. Typical construction materials for staticmixer components include stainless steel, polypropylene, Teflon™,polyvinylidene fluoride (“PVDF”), polyvinyl chloride (“PVC”),chlorinated polyvinyl chloride (“CPVC”) and polyacetal.

“Turbulent flow” is a less orderly flow regime that is characterized byeddies or small packets of fluid particles which result in lateralmixing.

Unless otherwise noted, all component or composition levels are inreference to the active portion of that component or composition and areexclusive of impurities, for example, residual solvents or by-products,which may be present in commercially available sources of suchcomponents or compositions.

All percentages and ratios are calculated by total composition weight,unless indicated otherwise.

It should be understood that every maximum numerical limitation giventhroughout this disclosure is deemed to include each and every lowernumerical limitation as an alternative, as if such lower numericallimitations were expressly written herein. Every minimum numericallimitation given throughout this disclosure is deemed to include eachand every higher numerical limitation as an alternative, as if suchhigher numerical limitations were expressly written herein. Everynumerical range given throughout this disclosure is deemed to includeeach and every narrower numerical range that falls within such broadernumerical range, as if such narrower numerical ranges were all expresslywritten herein. By way of example, the phrase from about 2 to about 4includes the whole number and/or integer ranges from about 2 to about 3,from about 3 to about 4 and each possible range based on real (e.g.,irrational and/or rational) numbers, such as from about 2.1 to about4.9, from about 2.1 to about 3.4, and so on.

The preceding is a simplified summary of the disclosure to provide anunderstanding of some aspects of the disclosure. This summary is neitheran extensive nor exhaustive overview of the disclosure and its variousaspects, embodiments, and configurations. It is intended neither toidentify key or critical elements of the disclosure nor to delineate thescope of the disclosure but to present selected concepts of thedisclosure in a simplified form as an introduction to the more detaileddescription presented below. As will be appreciated, other aspects,embodiments, and configurations of the disclosure are possibleutilizing, alone or in combination, one or more of the features setforth above or described in detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are incorporated into and form a part of thespecification to illustrate several examples of the present disclosure.These drawings, together with the description, explain the principles ofthe disclosure. The drawings simply illustrate preferred and alternativeexamples of how the disclosure can be made and used and are not to beconstrued as limiting the disclosure to only the illustrated anddescribed examples. Further features and advantages will become apparentfrom the following, more detailed, description of the various aspects,embodiments, and configurations of the disclosure, as illustrated by thedrawings referenced below.

FIG. 1 is a block diagram according to a first embodiment of thedisclosure;

FIG. 2 is a block diagram according to another embodiment;

FIG. 3 is a block diagram according to another embodiment;

FIG. 4 is a block diagram according to another embodiment;

FIG. 5 is a block diagram according to another embodiment;

FIG. 6 is a block diagram according to yet another embodiment;

FIG. 7 is a block diagram according to yet another embodiment;

FIG. 8 is a block diagram according to yet another embodiment;

FIG. 9 is a block diagram according to yet another embodiment;

FIG. 10 is a block diagram according to yet another embodiment;

FIG. 11 is a block diagram according to yet another embodiment;

FIG. 12 is a prior art depiction of the dependency of flow division in astatic mixing device to the number of baffles or mixing elements in thestatic mixing device;

FIGS. 13A and 13B are a prior art depiction of how flow division andradial mixing can occur in a static mixing device;

FIG. 14 is a block diagram of according to an embodiment;

FIGS. 15A and 15B depict an in-line mixing device in front and sideviews according to an embodiment;

FIGS. 16A and 16B depict an in-line mixing device in front viewsaccording to an embodiment;

FIG. 17 depicts control logic for an in-line mixing device havingmultiple operating modes according to an embodiment;

FIG. 18A and 18B are renderings of a movable in-line mixing deviceaccording to an embodiment;

FIG. 19A and 19B are renderings of a movable in-line mixing deviceaccording to an embodiment;

FIG. 20A and 20B are renderings of a movable in-line mixing deviceaccording to an embodiment;

FIG. 21A and 21B are renderings of a movable in-line mixing deviceaccording to an embodiment;

FIGS. 22A and 22B depict a movable in-line mixing device in front viewsaccording to an embodiment;

FIGS. 23A and 23B depict a movable in-line mixing device in front viewsaccording to an embodiment; and

FIG. 24 is a block diagram of a mixing device control system accordingto an embodiment.

It should be understood that the diagrams are provided for examplepurposes only, and should not be read as limiting the scope of thedisclosure. Many other configurations, including multiple sorbentinjection points and/or use of multiple static mixers, are fullycontemplated and included in the scope of the disclosure.

DETAILED DESCRIPTION Overview

The current disclosure is directed to an additive introduction system tointroduce one or more liquid and/or solid additives to controlcontaminant emissions from contaminant evolving facilities, such assmelters, autoclaves, roasters, steel foundries, steel mills, cementkilns, power plants, waste incinerators, boilers, and other contaminatedgas stream producing industrial facilities. Although any contaminant maybe targeted by the additive introduction system, typical contaminantsinclude one or more of acid gases (e.g., sulfur-containing compounds(such as sulfur dioxide and trioxide produced by thermal oxidation ofsulfides), nitrogen oxides (such as nitrogen monoxide and dioxide),hydrogen sulfide (H₂S), hydrochloric acid (HCl), and hydrofluoric acid(HF)), mercury (elemental and/or oxidized forms), carbon oxides (such ascarbon monoxide and dioxide), halogens and halides, particulates (e.g.,fly ash particles and other types of unburned carbon), and the like.Although the contaminant is typically evolved by combustion, it may beevolved by other oxidizing reactions, reducing reactions, and otherthermal processes such as roasting, pyrolysis, and autoclaving, thatexpose contaminated materials to elevated temperatures.

Static Mixing Device

FIG. 14 depicts a contaminated gas stream treatment process 1404 for anindustrial facility according to an embodiment. Referring to FIG. 14, acontaminated feed material 1408 is provided. In one application, thefeed material 1408 is combustible and can be any synthetic or natural,contaminate-containing, combustible, and carbon-containing material,including coal, petroleum coke, and biomass. The feed material 1408 canbe a high alkali, high iron, and/or high sulfur coal. In otherapplications, the present disclosure is applicable to noncombustible,contaminant-containing feed materials, including, without limitation,metal-containing ores, concentrates, and tailings.

The feed material 1408 is heated in thermal unit 1400 to produce acontaminated gas stream 1412. The thermal unit 104 can be any heatingdevice, including, without limitation, a dry or wet bottom furnace(e.g., a blast furnace, puddling furnace, reverberatory furnace,Bessemer converter, open hearth furnace, basic oxygen furnace, cyclonefurnace, stoker boiler, cupola furnace, a fluidized bed furnace, archfurnace, and other types of furnaces), boiler, incinerator (e.g., movinggrate, fixed grate, rotary-kiln, or fluidized or fixed bed,incinerators), calciners including multi-hearth, suspension or fluidizedbed roasters, intermittent or continuous kiln (e.g., ceramic kiln,intermittent or continuous wood-drying kiln, anagama kiln, bottle kiln,rotary kiln, catenary arch kiln, Feller kiln, noborigama kiln, or tophat kiln), or oven.

The contaminated gas stream 1412 generally includes a number ofcontaminants. A common contaminated gas stream 108 includes mercury,particulates (such as fly ash), sulfur oxides, nitrogen oxides,hydrochloric acid (HCl), other acid gases, carbon oxides, and unburnedcarbon.

The contaminated gas stream 1412 is optionally passed through the(pre)heater 200 to transfer some of the thermal energy of thecontaminated gas stream 1412 to air 1416 prior to input to the thermalunit 1400. The heat transfer produces a common temperature drop in thecontaminated gas stream 1420 of from about 500° C. to about 300° C. toproduce a cooled contaminated gas stream 1420 temperature commonlyranging from about 100 to about 400° C.

The cooled contaminated gas stream 1420 next passes into the additiveinjection system 1424, which injects an additive, such as a sorbent,into the cooled contaminated gas stream 1420, to form anadditive-containing gas stream 1428. The additive injection system 1424can be any suitable liquid or solid additive injection system includingthat described in copending U.S. application Ser. No. 13/045,076, filedMar. 10, 2011, and Ser. No. 13/645,138, filed Oct. 4, 2012, each ofwhich are incorporated fully herein by this reference. Other examplesinclude spray dry and dry injection systems optionally using one or morelances, compressors or pumps, educators, etc. Commonly, the additive isinjected through an array of lances positioned upstream of a particulatecontrol device, typically an electrostatic precipitator or fabricfilter.

The additive controls emissions of the selected or targeted contaminantin a treated gas stream 1432. Typically, the additive 1436 is entrainedin a carrier fluid, such as a carrier liquid or gas, when introduced byadditive introduction system 1424. To entrain the additive particleseffectively, the additive particles typically have a mean, median, andP₉₀ size of no more than about 100 microns and even more typicallyranging from about 2 to about 50 microns. The additive-containing fluid(which is mixture of the entrained additive particles and carrier gas)typically includes from about 0.10 to about 6.0 lbm material to lbm air(at standard temperature and pressure).

The additive 1436 employed depends on the contaminant targeted and canbe in any form before and after injection, whether a liquid, a solid, orsemi-solid. By way of example, an acid gas controlling sorbent caninclude an alkaline material, such as (hydrated) lime or an alkalineearth or alkali metal bicarbonate, to control emissions of nitrogenoxides (NO_(X)), sulfur oxides (SOx), hydrochloric acid (HCl), and/orhydrofluoric acid (HF) and an alkaline or alkali metal (e.g., sodium)sesquicarbonate (e.g., trona) to control emissions of sulfur oxides(SOx), hydrogen sulfide (H₂S), hydrochloric acid (HCl), and/orhydrofluoric acid (HF). Other acid gas controlling sorbents includemetal oxides, such as magnesium oxide or magnesium hydroxide, alkalineearth and alkali metal carbonates, such as sodium carbonate (“sodaash”), and alkaline earth and alkali metal bicarbonates. The byproductof the reaction between the acid gas controlling sorbent and acid gas istypically a particulate that is removed by a particulate control device.A mercury capture sorbent 400 can include halogens and/or halides. Aswill be appreciated, halogens and halides can oxidize elemental mercuryand the resulting oxidized mercury can be collected on a particulateand/or powdered activated carbon (“PAC”) for subsequent removal by aparticulate control device. Another mercury capture sorbent 400 is PAC,which can control not only mercury but also a variety of othercontaminants, such as gaseous heavy metals dioxins, furans, andhydrocarbons, and which itself is removed as a particulate by aparticulate control device. Often, the additive includes both acid gascontrolling and mercury capture sorbents. The presence of acid gases caninterfere with mercury sorption on carbon-based mercury sorbents. Aswill be appreciated, other additives may be used depending on thecontaminant(s) targeted.

In other examples, the additive 1436 can be one or more flue gasconditioning agent(s), such as compounds comprising one or more nitratesand nitrites. Exemplary flue gas conditioning agents include those inU.S. Pat. Nos. 6,001,152; 5,833,736; 5,893,943; 5,855,649; 6,267,802;and 6,797,035, each of which is incorporated herein by reference intheir entireties.

Although the carrier fluid for the additive can be any substantially(chemically) inert fluid (relative to the additive), a common carriergas is water or air. Typically, the carrier fluid includes a minoramount, more typically no more than about 400 ppm_(v), and even moretypically no more than about 390 ppm_(v) of an additive reactivecomponent, such as carbon dioxide, that reacts with the additive. Forexample, carbon dioxide reacts with lime to produce calcium carbonate.

The distribution of sorbent is typically non-ideal (non-uniform) in theadditive-containing gas stream. An increase in lance coverage of theadditive injection system or additional additive injection often failsto provide a more uniform distribution due to mass transfer limitations.For such situations, a fixed (static) gas mixing device installedupstream or downstream of additive injection can improve particledistribution without requiring long duct runs and higher plant capitalcosts. In particular, the mixing device is typically located immediatelyupstream of the additive injection for a liquid additive as the liquidadditive can deposit on the mixing device, thereby adversely hinderingits performance over time in the absence of cleaning For a solidadditive, the mixing device can be located not only immediately upstreambut also downstream of the additive injection system.

In the latter plant configuration, the additive-containing gas stream1428 passes a static mixing device 300, which causes additive mixing inthe gas stream, thereby providing a mixed gas stream 1440 having,compared to the additive-containing gas stream 1428, an increaseduniformity through the gas stream not only of additive distribution butalso of temperature and/or velocity profile. This can be true for eithersingle-phase or multiphase gas streams. As will be appreciated, asingle-phase gas flow contains multiple gases while a multiphase flowcontains at least one gas and at least one particulate solid, typicallya sorbent additive. While FIG. 14 is discussed with reference to a dryadditive only and downstream mixing, it is to be understood that thediscussion of FIG. 14 applies equally to a liquid or dry additiveinjection immediately upstream or downstream of a mixing device.

There are a variety of static mixing devices 300 designed to achievebetter gas mixing, temperature de-stratification, and more uniformvelocity profile with minimal pressure drop. The static mixing device300, for example, can be an arrangement of stationary, fixed, and/orstatic fan-type blades (or mixing elements) that induce turbulence andencourage mixing in the gas stream. The static mixing device 300 can bea plurality of stationary, fixed, and/or static baffles or plates (ormixing elements) on the interior wall of a duct that extend into theduct. The baffles may be straight or curved and may be offset in theflow direction or in plane. Of course, the static mixing device also maybe a combination of these embodiments or any other design that wouldencourage mixing in the gas stream.

An example of a static mixing device 300 is the Series IV Air Blender™or Blender Box™ manufactured by Blender Products, Inc. This staticmixing device 300 is described in U.S. Pat. No. 6,595,848, which isincorporated herein by this reference. As described in U.S. Pat. No.6,595,848, the static mixing device has multiple radially extendingvanes (or mixing elements) diverging away from a center of an enclosureand terminating at outer distal ends of the vanes positioned adjacent tothe enclosure. The vanes can have an inner section traversing a firstdistance from the center and an outer section connected to the innersection along a leading radial edge of the vane. The outer sectiontraverses a remaining distance from the inner section to the enclosure.The inner section curves rearwardly in a first direction away from theleading radial edge, and the outer section curves rearwardly in a seconddirection away from the leading radial edge.

The static mixing device 300 typically is a housed-elements design inwhich the static mixing device elements include a series of stationary,fixed, rigid, and/or static mixing elements made of metal, ceramic,and/or a variety of materials stable at the temperature of thecontaminated gas stream. Similarly, the mixing device housing, which iscommonly the duct for transporting the contaminated waste gas, can bemade of the same materials. Two streams of fluids, namely thecontaminated gas stream and the injected sorbent stream are introducedinto the static mixing device 300. As the streams move through themixing device, the non-moving or stationary mixing elements continuouslyblend the components of the streams to form a mixed gas stream having asubstantially homogeneous composition. Complete mixing commonly dependson many variables including the fluids' properties, tube inner diameter,number of elements and their design.

The mixing elements, particularly when helically-shaped, cansimultaneously produce patterns of flow division and radial mixing. Withreference to FIGS. 13A and 13B, the static mixing device 300 can effectflow division and/or radial mixing. With respect to FIG. 13A, flowdivision can occur in the mixed gas stream. In laminar flow, a gasstream 1300 can divide, as shown by the gas flow arrows, at the leadingedge of each mixing element 1304 of the mixing device 300 and follow thechannels created by the mixing element 1304 shape (which is curved orarcuate in FIG. 13A). With respect to FIG. 13B, radial mixing can,alternatively or additionally, occur in the mixed gas stream. In eitherturbulent flow or laminar flow, rotational circulation 1308 of the gasstream around its hydraulic center in each channel of the mixing devicecan cause radial mixing of the gas stream. The gas stream is commonlyintermixed to reduce or eliminate radial gradients in temperature,velocity and/or gas stream composition. In most applications, the gasstream will have non-laminar or turbulent flow.

With reference to FIG. 12, flow division in a static mixing device usingbaffles as mixing elements is a function of the number of mixingelements in the mixing device. At each succeeding mixing element 1304,the two channels can be further divided, resulting in an exponentialincrease in stratification. The number of striations normally producedis 2^(n) where ‘n’ is the number of mixing elements 1304 in the mixingdevice. As shown by FIG. 12, the number of flow striations is two forone mixing element, four for two mixing elements, eight for three mixingelements, sixteen for four mixing elements, and thirty-two for fivemixing elements. While FIGS. 12, 13A and 13B are discussed withreference to additive injection upstream of the mixing device, it is tobe understood that the discussion applies equally to additive injectionupstream or downstream of the mixing device.

In most applications, the additive-containing gas stream 1428, at theinput to the mixing device, has laminar flow, and the number of mixingelements in the static mixing device 300 is typically at least one, moretypically at least two, and even more typically ranges from about threeto about fifty. Both flow division and radial mixing normally occur inpower plant flue gas treatment applications. In such applications, theflue gas velocity typically ranges from about 5 to about 50 m/s and moretypically from about 12 to about 20 m/s for a power plant. In otherapplications, the additive-containing gas stream 1428, at the input tothe mixing device, has turbulent flow, and only radial mixing (andsubstantially no flow division) occurs.

The static mixing device 300 is typically positioned a distance upstream(or downstream) of the particulate removal device to allow adequatemixing and contaminant-additive particle interaction and a distance(upstream or) downstream of the point(s) of additive injection by theadditive injection system 1424 to allow time for adequate dispersion ofthe additive particles in the gas stream. In the mixed gas stream, thedistance from an output of the static mixing device to an input of adownstream particulate control device can be at least about one timesthe hydraulic diameter of the pipe or duct. While determined by theconfiguration of the power plant, the maximum distance from the outputof the static mixing device to the input of the particulate controldevice is commonly no more than about ten times the hydraulic diameter.The distance from an upstream point of introduction of the additive intothe contaminated gas stream to an input to the static mixing device (orfrom an output of the static mixing device to a downstream point ofintroduction of the additive into the contaminated gas stream) istypically no more than about one times the hydraulic diameter, moretypically no more than about 0.75 times the hydraulic diameter, and moretypically no more than about 0.50 times the hydraulic diameter. Whiledetermined by the configuration of the power plant, the minimum distancefrom the point of introduction of the additive into the contaminated gasstream to the downstream input (or upstream output) to the static mixingdevice is commonly at least about 0.1 times the hydraulic diameter.

Referring again to FIG. 14, the mixed gas stream 1440 passes throughparticulate control device 500 to remove most of the particulates (andtargeted contaminant and/or derivatives thereof) from the mixed gasstream 1440 and form a treated gas stream 1432. The particulate controldevice 500 can be any suitable device, including a wet or dryelectrostatic precipitator, particulate filter such as a baghouse, wetparticulate scrubber, and other types of particulate removal device.

The treated gas stream 1432 is emitted, via gas discharge 1450 (e.g.,stack), into the environment.

Exemplary Process Configurations

A number of exemplary configurations of the above process will now bediscussed with reference to FIGS. 1-11.

FIG. 1 depicts a process in which a mercury capture sorbent is injectedat an injection location upstream of the static mixing device 300.Referring to FIG. 1, a boiler 100 combusts a combustible feed material,such as coal, and generates a mercury and acid gas-containing gas stream110. The static mixing device 300 is placed in the flow stream of themercury and acid gas-containing gas stream 110. In this configuration,the static mixing device 300 is positioned downstream of the injectionlocation of a sorbent 400 injected by the additive injection system (notshown). The injected sorbent 400 can be a mercury capture sorbent, suchas a halogen or halogenated compound or halogen impregnated sorbentparticle, such as halogenated activated carbon. The injected sorbent 400combines with mercury in the mercury and acid gas-containing gas stream110 and forms mercury-containing particulates. A particulate controldevice 500 then removes at least some, and typically most, of themercury-containing and other particulates from the mercury and acidgas-containing gas stream 110. As shown by the dashed line 104, themercury capture sorbent can also or alternatively be injected at alocation downstream of the static mixing device 300.

FIG. 2 depicts a process in which an acid gas-controlling sorbent, suchas an alkaline sorbent 410, is injected at an injection locationupstream of the static mixing device 300. Referring to FIG. 2, theboiler 100 combusts the combustible feed material and generates themercury and acid gas-containing gas stream 110. The static mixing device300 is positioned in the flow stream of the mercury and acidgas-containing gas stream 110. In this configuration, the static mixingdevice 300 is placed downstream of the injection location of a sorbent410 injected by the additive injection system (not shown). In one aspectof this configuration, the injected sorbent 410 is an alkaline sorbent.As noted above, the sorbent 410 can be any other acid-controllingsorbent or mixture of acid gas-controlling sorbents. The injectedsorbent 410 reacts with or otherwise reduces the concentration of SO₃ orother acid gases in the mercury and acid gas-containing gas stream 110.In this configuration, carbonaceous materials in the mercury and acidgas-containing gas stream 110, such as fly ash, may combine with themercury in the mercury and acid gas-containing gas stream 110 due to thelower concentrations of SO₃. The particulate control device 500 thenremoves at least some, and typically most, of the mercury containing andother particulates (such as the byproducts of acid gas removal) from themercury and acid gas-containing gas stream 110. As shown by the dashedline 204, the alkaline sorbent can also or alternatively be injected ata location downstream of the static mixing device 300.

FIG. 3 illustrates a process in which an acid gas-controlling sorbent,such as an alkaline sorbent 410, is injected at an injection locationupstream of the static mixing device 300 and a mercury capture sorbentis injected at an injection location downstream of the static mixingdevice 300. Referring to FIG. 3, the boiler 100 combusts the combustiblefeed material and generates a mercury and acid gas-containing gas stream110. The static mixing device 300 is placed in the flow stream of themercury and acid gas-containing gas stream 110. In this configuration,the static mixing device 300 is placed in the mercury and acidgas-containing gas stream 110 between the injection location of a firstsorbent 410 injected by the additive injection system (not shown) andthe injection location of a second sorbent 400 injected by the additiveinjection system (not shown). In some embodiments, the first injectedsorbent 410 is an alkaline sorbent to react with one or more acid gases,and the second injected sorbent 400 is a mercury capture sorbent. Asnoted above, the sorbent 410 can be any other acid-controlling sorbentor mixture of acid gas-controlling sorbents. The first injected sorbent410 reacts with or otherwise reduces the concentration of SO₃ or otheracid gases in the mercury and acid gas-containing gas stream. These acidgases could potentially interfere with the second injected sorbent's 400ability to combine with or otherwise capture mercury. The secondinjected sorbent 400 then combines with mercury in the mercury and acidgas-containing gas stream 110 and forms mercury containing particulates.The particulate control device 500 then removes at least some, andtypically most, of the mercury-containing and other particulates (suchas the byproducts of acid gas removal) from the mercury and acidgas-containing gas stream 110. As shown by the dashed line 304, thealkaline sorbent can also or alternatively be injected at a locationdownstream of the static mixing device 300.

FIG. 4 depicts a process in which an acid gas-controlling sorbent, suchas an alkaline sorbent 410, is injected at an injection locationupstream of the static mixing device 300, a mercury capture sorbent isinjected at an injection location downstream of the static mixing device300, and an electrostatic precipitator (“ESP”) 520 is located downstreamof the air heater 200 and upstream of the static mixing device 300 andthe sorbent injection locations. In this embodiment, the particulatecollection device is typically a TOXECON baghouse 510. Referring to FIG.4, the boiler 100 combusts the combustible feed material and generates amercury and acid gas-containing gas stream 110. The static mixing device300 is placed in the flow stream of the mercury and acid gas-containinggas stream 110. In this configuration, the static mixing device 300 isplaced in the mercury and acid gas-containing gas stream 110 between thelocation of injection by the additive injection system (not shown) of afirst injected sorbent 410 and the location of injection by the additiveinjection system (not shown) of a second injected sorbent 400. In someembodiments, the first injected sorbent 410 is an alkaline sorbent, andthe second injected sorbent 400 is a mercury capture sorbent. As notedabove, the sorbent 410 can be any other acid-controlling sorbent ormixture of acid gas-controlling sorbents. The first injected sorbent 410reacts with or otherwise reduces the concentration of SO₃ or other acidgases in the mercury and acid gas containing gas stream. The secondinjected sorbent 400 then combines with mercury in the mercury and acidgas-containing gas stream 110 and forms mercury-containing particulates.In one aspect of this configuration, the ESP 520 is downstream of theair heater 200 and upstream of each of the following: the injectionlocation of the first injected sorbent 410, the static mixing device300, and the injection location of the second injected sorbent 400. Inanother aspect of this configuration, alkaline sorbent and mercurycontaining particles are collected with a TOXECON baghouse 510. TheTOXECON baghouse 510 removes at least some, and typically most, of themercury-containing and other particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110. As shown by the dashed line 404, the alkaline sorbent can also oralternatively be injected at a location downstream of the static mixingdevice 300.

In some embodiments, the static mixing device 300 will be utilized incombination with Dry Sorbent Injection (“DSI”)/Activated CarbonInjection (“ACI”) dual injection. In this configuration, the staticmixing device 300 is placed in the mercury and acid gas-containing gasstream 110 between the location of injection by the additive injectionsystem (not shown) of a first injected sorbent 410 and the location ofinjection by the additive injection system (not shown) of a secondinjected sorbent 400. In this configuration, the first injected sorbent410 is an alkaline sorbent, and the second injected sorbent 400 isactivated carbon. As noted above, the sorbent 410 can be any otheracid-controlling sorbent or mixture of acid gas-controlling sorbents.This embodiment will allow for maximal utilization of alkaline materialand reduction of acid gases such as SO₃ prior to activated carboninjection for mercury control. Ultimately, this can reduce sorbent usagefor a given sorbent injection rate, thereby reducing operating costsand/or achieving maximal combined removal of acid gases and mercury. Asshown by the dashed line 504, the mercury capture sorbent can also oralternatively be injected at a location downstream of the static mixingdevice 300.

FIGS. 5 through 11 demonstrate additional embodiments of the disclosure.These embodiments demonstrate potential configurations applying a staticmixing device 300 to hot-side sorbent injection applications. As will beappreciated, “hot side” refers to a location upstream of the air(pre)heater 200. Typical contaminated gas stream temperatures upstreamof the air (pre)heater 200 are at least about 300° C. and more typicallyrange from about 350 to about 450° C. and downstream of the air(pre)heater 200 are no more than about 250° C. and more typically rangefrom about 120 to about 200° C.

FIG. 5 shows injection of a mercury capture sorbent 400 upstream of boththe static mixing device 300 and the air (pre)heater 200 (which islocated downstream of the static mixing device 300). The particulatecontrol device 500 then removes at least some, and typically most, ofthe mercury-containing and other particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110.

FIG. 6 shows injection of an acid gas controlling sorbent, such as analkaline sorbent 410, upstream of both the static mixing device 300 andthe air (pre)heater 200 (which is located downstream of the staticmixing device 300). The particulate control device 500 then removes atleast some, and typically most, of the particulates (such as thebyproducts of acid gas removal) from the mercury and acid gas-containinggas stream 110.

FIG. 7 shows injection of an acid gas controlling sorbent, such as analkaline sorbent 410, upstream of the air (pre)heater 200 and staticmixing device 300 (which is also positioned upstream of the air(pre)heater 200 and of a mercury capture sorbent 400 downstream of theair (pre)heater and static mixing device 300 but upstream of theparticulate control device 500. The particulate control device 500 thenremoves at least some, and typically most, of the mercury-containing andother particulates (such as the byproducts of acid gas removal) from themercury and acid gas-containing gas stream 110.

FIG. 8 shows injection of an acid gas controlling sorbent, such as analkaline sorbent 410, upstream of the air (pre)heater 200 and staticmixing device 300 (which is positioned downstream of the air (pre)heater200 (or on the cold-side) and of a mercury capture sorbent 400downstream of the air (pre)heater and static mixing device 300 butupstream of the particulate control device 500. The particulate controldevice 500 then removes at least some, and typically most, of themercury-containing and other particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110.

FIG. 9 shows injection of an acid gas controlling sorbent, such as analkaline sorbent 410, upstream of the air (pre)heater 200 and staticmixing device 300 (which is positioned downstream of the air (pre)heater200 (or on the cold-side) and of a mercury capture sorbent 400downstream of the air (pre)heater 200 and upstream of the static mixingdevice 300 and the particulate control device 500. The particulatecontrol device 500 then removes at least some, and typically most, ofthe mercury-containing and other particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110.

FIG. 10 shows injection of an acid gas controlling sorbent, such as analkaline sorbent 410, upstream of both the static mixing device 300 andthe air (pre)heater 200 (which is located upstream of the static mixingdevice 300). The particulate control device 500 then removes at leastsome, and typically most, of the particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110.

FIG. 11 shows injection of a mercury capture sorbent 400 upstream ofboth the static mixing device 300 and the air (pre)heater 200 (which islocated upstream of the static mixing device 300). The particulatecontrol device 500 then removes at least some, and typically most, ofthe mercury-containing and other particulates (such as the byproducts ofacid gas removal) from the mercury and acid gas-containing gas stream110.

With reference to FIGS. 5-11, the mercury capture sorbent 400 as shownby dashed line 504 (FIG. 5), the alkaline sorbent 410 as shown by dashedline 604 (FIG. 6), the alkaline sorbent 410 as shown by dashed line 704(FIG. 7), the alkaline sorbent 410 as shown by dashed line 804 (FIG. 8),the alkaline sorbent 410 as shown by dashed line 904 and mercury capturesorbent 400 as shown by dashed line 908 (FIG. 9), the alkaline sorbent410 as shown by dashed line 1004 (FIG. 10), and the mercury capturesorbent 400 as shown by dashed line 1104 (FIG. 11) can be introducedinto the contaminated gas stream downstream of the static mixing device300.

FIGS. 15A and 15B show an in-line static or dynamic (or non-static)mixing device 1500, with plural mixing elements 1520, that has a reducedsize relative to the cross-sectional area of the duct 1504 such that gasflow through a substantial portion of the duct area 1512 will not passthrough the mixing device 1500. As can be seen, the duct has a heightH_(D) of H_(a)+H_(b) and a width W_(D) of W_(a)+W_(b) while the mixingdevice 1500 has a height H_(a) and a width W_(b). Typically, the mixingdevice height H_(a) is no more than about 75%, more typically no morethan about 70%, more typically no more than about 65%, more typically nomore than about 60%, more typically no more than about 55%, and evenmore typically no more than about 50% of the duct height H_(D).Typically, the mixing device width W_(b) is no more than about 75%, moretypically no more than about 70%, more typically no more than about 65%,more typically no more than about 60%, more typically no more than about55%, and even more typically no more than about 50% of the duct widthW_(D). Typically, the cross-sectional area of the mixing device normalto a direction of gas flow 1516 is no more than about 75%, moretypically no more than about 70%, more typically no more than about 65%,more typically no more than about 60%, more typically no more than about55%, and even more typically no more than about 50% of thecross-sectional area of the duct normal to the direction of gas flow1516. When the additive is injected by the additive injection system1424 immediately downstream (as shown in FIG. 15B) of the mixing device1500 with the tip 1528 of the lance 1524 being located behind (asdetermined by the gas flow) the mixing device 1500, the gas first flowsthrough the mixing device, and the additive is injected by the tip 1528of the lance 1524 into the more turbulent gas flow. As will beappreciated, laminar gas flow is typically upstream of the mixing device1500 while non-laminar or turbulent flow is downstream of the mixingdevice 1500. The reduced cross-sectional area of the mixing device caninduce gas stream turbulence for better additive distribution whilereducing pressure drop relative to larger mixing devices.

Other configurations are possible involving downstream sorbent injectionand reduced sized mixing devices, such as mixing device 1500,substituted for the mixing devices of FIGS. 1-11. As shown by the dashedline 504 of FIG. 5, the mercury capture sorbent can also oralternatively be injected at a location downstream of the reduced sizedstatic mixing device 300. As shown by the dashed line 604 of FIG. 6, thealkaline sorbent can also or alternatively be injected at a locationdownstream of the reduced sized static mixing device 300. As shown bythe dashed line 704 of FIG. 7, the alkaline sorbent can also oralternatively be injected at a location downstream of the reduced sizedstatic mixing device 300. As shown by the dashed line 804 of FIG. 8, thealkaline sorbent can also or alternatively be injected at a locationdownstream of the static mixing device 300. As shown by the dashed lines904 and 908 of FIG. 9, the alkaline sorbent and mercury capture sorbent,respectively, can also or alternatively be injected at a locationdownstream of the reduced sized static mixing device 300. As shown bythe dashed line 1004 of FIG. 10, the alkaline sorbent can also oralternatively be injected at a location downstream of the reduced sizedstatic mixing device 300. As shown by the dashed line 1104 of FIG. 11,the mercury capture sorbent can also or alternatively be injected at alocation downstream of the reduced sized static mixing device 300.

Not shown, but contemplated by the disclosure, are additionalconfigurations utilizing hot-side injection of one or more sorbents anda hot-side ESP (or other particulate removal device), with the staticmixing device 300 placed in between and upstream or downstream of theadditive injection location. The static mixing device 300, whetherreduced or full sized relative to the duct, may be helpful with hot-sideinjection applications, that is, applications where a sorbent isinjected upstream of the air (pre)heater 200. While such configurationsgenerally benefit from increased residence time and the associatedimprovement in sorbent distribution, the static mixing device 300 cancontribute an even more complete sorbent distribution.

With any hot-side sorbent injection application, the static mixingdevice 300 could be placed either upstream or downstream of the air(pre)heater. Typically, the plant configuration will dictate theappropriate location. Variables include length of flow path available,requirements for distribution of the sorbent or velocity and temperatureprofiles, and location of the particulate control device (includinghot-side or cold-side ESP).

Further contemplated is the use of a static mixing device 300 with otherwet or dry sorbents (e.g., wet flue gas desulfurization additives), thatwere not specifically named in this disclosure, including sorbentsapplied to the fuel and sorbents injected into the furnace in any of agas, liquid, or solid phase. Although the disclosure specificallytargets dry sorbent (including activated carbon and DSI) injection, itis contemplated that use of a static mixing device 300 would furtherimprove uniformity of distribution for these sorbents, as a well asoffering uniformity benefits to velocity and temperature profiles of theresulting contaminated gas stream.

Variable Pressure Drop Mixing Device

Referring to FIGS. 15A and 15B, the static or dynamic mixing device 1500can provide a variable pressure drop by moving from a first position ororientation relative to the direction of gas flow 1516 in a firstoperational mode to a different second position or orientation relativeto the direction of gas flow 1516 in a second operational mode. Thevariable position can be effected by rotation (such as by a motor,hydraulic, or electromagnetic system) of the mixing device (as shown byrotational arrows 1538) about the rotating member 1534, which rotatesthe mixing device around a vertical axis X 1542. In the firstoperational mode in which a front plane 1550 of the mixing device 1500is substantially normal to the direction of gas flow 1516, a maximumvolume of gas contacts and passes through the mixing device for aselected time interval. Thus, in the first operational mode, thepressure drop of the gas induced by the mixing device and the level ofturbulent flow (and degree of mixing) downstream of the mixing device1500 are substantially maximized. In the second operational mode inwhich the front plane 1550 of the mixing device 1500 is substantiallyparallel to the direction of gas flow 1516 (not shown), a minimum volumeof gas contacts and passes through the mixing device over the selectedtime interval (e.g., the mixing device is substantially free of contactwith the gas flow). Thus, in the second operational mode, the pressuredrop of the gas induced by the mixing device and the level of turbulentflow (and degree of mixing) downstream of the mixing device 1500 aresubstantially minimized. The angular orientation of the mixing devicerelative to the direction of gas flow 1516 can be varied to realizedifferent levels of pressure drop between the maximum and minimumpressure drop in the first and second operational modes and passdifferent volumes of gas over the selected interval between the minimumand maximum amounts in the first and second operational modes. Likewise,the angular orientation of the mixing device 1500 relative to thedirection of gas flow 1516 can be varied to realize different levels ofturbulent flow (and degree of mixing) downstream of the mixing device1500.

Referring to FIGS. 22A and 22B, another static or dynamic mixing deviceconfiguration is depicted. The mixing device 2200, as in the mixingdevice of FIGS. 15A and 15B, is mounted on a vertically extendingrotating member 2204 and includes multiple mixing elements 2212. Themixing device 2200 occupies most of the cross-sectional area of the duct1504 (with the direction of gas flow being into the page). The actuator2208 rotates the mixing device 2200 from a first orientation in thefirst operational mode to a second orientation in the second operationalmode (of FIG. 22B) in which the gas stream contacts an edge 2216 of themixing device.

Referring to FIGS. 23A and 23B, another static or dynamic mixing deviceconfiguration is depicted. The mixing device 2300 is mounted on ahorizontally extending rotating member 2304 and includes multiple mixingelements 2312. The mixing device 2300 occupies most of thecross-sectional area of the duct 1504 (with the direction of gas flowbeing into the page). The motor 2308 rotates the mixing device 2300 froma first orientation in the first operational mode in which the gasstream contacts a front face or plane 2316 of the mixing device to asecond orientation in the second operational mode in which the gasstream contacts a side edge 2320 of the mixing device. Thus, in thefirst operational mode, the pressure drop of the gas induced by themixing device and the level of turbulent flow (and degree of mixing)downstream of the mixing device 1500 are substantially maximized while,in the second operational mode, the pressure drop of the gas induced bythe mixing device and the level of turbulent flow (and degree of mixing)downstream of the mixing device 1500 are substantially minimized.

FIGS. 16A and B depict another static or dynamic mixing deviceconfiguration to realize results similar to those of FIGS. 15A and 15B.The mixing device 1600 comprises plural mixing elements 1604 configuredas contoured louvers or vanes mounted within a supporting frame. Themixing device typically is a housed-elements design in which the staticmixing device elements include a series of mixing elements made ofmetal, ceramic, and/or a variety of materials stable at the temperatureof the contaminated gas stream. Similarly, the mixing device housing canbe made of the same materials. Each mixing element is rotatably mountedwithin the supporting frame on a corresponding rotating member 1608,which is in turn engaged with an actuator 1612. The actuator 1612rotates simultaneously the mixing elements 1604 by the respectiverotating member 1608 from a first orientation relative to the directionof gas flow to a different second angular orientation relative to thedirection of gas flow. While maintaining the position of the mixingdevice supporting frame stationary, the mixing device 1500 can provide avariable pressure drop by moving the mixing elements from a firstposition or orientation relative to the direction of gas flow 1516 in afirst operational mode to a different second position or orientationrelative to the direction of gas flow 1516 in a second operational mode.In the second operational mode in which a front plane of each of themixing elements is substantially parallel to the direction of gas flow1516 (FIG. 16B) and the contoured surfaces of the mixing elements do notcontact the gas stream, a minimum (or no) volume of gas passes throughthe mixing element for a selected time interval (as an edge of themixing element contacts the gas rather than the gas mixing portion ofthe mixing element). Thus, in the second operational mode, the pressuredrop of the gas induced by the mixing device and level of downstreamturbulent flow and degree of mixing are substantially minimized. In thefirst operational mode in which the front plane of the mixing elementsis substantially normal to the direction of gas flow 1516 (FIG. 16A) andthe contoured surfaces of the mixing elements contact the gas stream, amaximum volume of gas stream contacts and passes through the mixingdevice over the selected time interval (as the edge of the mixingelement is parallel to the direction of gas flow and the gas mixingportion of the mixing element contacts the gas stream). Thus, in thefirst operational mode, the pressure drop of the gas induced by themixing device and level of downstream turbulent flow and degree ofmixing are substantially maximized. The angular orientation of themixing device relative to the direction of gas flow 1516 can be variedto realize different levels of pressure drop between the maximum andminimum pressure drops in the first and second operational modes andpass different volumes of gas, and produce different degrees of mixing,over the selected internal between the minimum and maximum amounts inthe first and second operational modes.

A number of other exemplary configurations of the rotatable staticmixing device system will now be discussed with reference to FIGS. 18A,18B, 19A, 19B, 20A, 20B, 21A and 21B.

FIG. 18B shows a static mixing system 1800 comprising an array of staticmixing devices 1804. The array may be organized with a plurality ofstatic mixing devices in rows or columns. As depicted, the arraycomprises two columns, each containing two rigidly connected staticmixing devices 1804 stacked vertically. The columns themselves rotateindependently of one another. Each column contains a rotational axis1801 that runs through the center of the column (e.g., through thecenter of mass of the column and/or the axis of symmetry). Each columncan be rotated, clockwise, counter-clockwise, or both, about the centralrotational axis 1801, such that the mixing elements 1808 of the staticmixing devices 1801 will be in plane with the gas stream. In otherwords, the system 1800 as depicted induces turbulence in a gas stream.The columns can be turned 90 degrees such that the system 1800 will havea smaller cross section, the mixing elements will not be exposed to thegas stream, turbulence will not be induced in the gas stream, and thestatic mixing system will create a lower pressure drop.

FIG. 18A shows a top view of the static mixing system. A actuatorlinkage system 1812 is provided. The actuator linkage system 1812 turnsthe columns about the axis 1801. A limit switch can limit rotationbetween the first and second orientations. Typically, the rotation islimited to about 90 degrees rotation.

FIG. 19B shows a static mixing system 1900 comprising an array of staticmixing devices. As depicted, the array comprises five columns 1904 a-e,each containing five static mixing devices 1908 a-d stacked vertically.Each static mixing device 1908 has three static mixing elements 1910 atits center. Three rotational axes 1920 run through each column of staticmixing devices. The static mixing elements 1910 are attached to therotational axes 1920, such that a static mixing element of a staticmixing device is attached to the corresponding mixing element of theother static mixing devices in the same column but not to static mixingdevices in other columns. As shown in FIG. 19A, the mixing elements 1910can be rotated about the axes 1920. In operation, the mixing elements1910 are set at an angle to the duct or pipe. When gas passes throughthe static mixing system, the angle of the mixing elements 1910 inducesturbulence in the gas stream and causes a pressure drop. When the mixingelements 1910 are turned such that they are substantially in plane withthe flow of the gas stream, the pressure drop is minimized (andturbulence is somewhat reduced).

FIG. 21A and 21B show a detail of one static mixing device 1908 withrotatable mixing elements 1910 as depicted in this embodiment. Theorientation and configuration of each of the rotational mixing elements1910 in each mixing device in each column are shown in FIG. 19B abovethe respective column in FIG. 19B. The orientations of the mixingelements 1910 are in positions to induce maximum turbulence in the gasstream. Rotating the mixing elements to be in plane with the directionof gas flow induces a minimum degree of gas stream turbulence andminimizes the pressure drop.

FIG. 20B shows a static mixing system 2000 comprising an array of staticmixing devices 2104. As depicted, the array comprises five columns 2108a-e, each containing five static mixing devices 2104 a-e stackedvertically. Each static mixing device 2104 has mixing elements 2112extending radially from its center. As depicted in FIG. 20A, the mixingelements 2112 may be rotated about an axis, so as to change the angle atwhich the mixing element is situated with respect to the direction offlow of the gas stream.

The number of mixing devices in an N×M array depends on the application.Each of N and M typically ranges from 1 to 25, more typically from 2 to20, more typically from 2 to 15, and more typically from 2 to 10. In anexample of a 20′×20′ duct, 4′ square mixing devices can be placed in a5×5 array to cover substantially the cross section of the duct (seeFIGS. 19A-B and 20A-b). In this configuration, the mixing devices areinstalled in columns. For example, one column installation might be 4′wide, and 20′ tall. The column would comprise 5 mixing devices stackedon top of each other. Four such columns would be installed to cover thefull cross section of the flue duct. In this configuration, the columnsmight be installed such that each column can be “turned” around a pivotpoint. All columns can be turned (similar to vents in a car) so that theduct cross section is no longer substantially covered by mixing devices.In an example where the mixing devices are 1′ deep, when the mixingdevice columns are fully “open,” the duct cross section would now besubstantially open and only be blocked by 5 columns, 1′ wide each.Columns could be installed as rows (horizontal installation rather thanvertical). Configurations can be envisioned where the structure of theblender array remains in place, but the blades themselves are openedclosed in response to a mechanical stimulus.

While the various mixing systems of FIGS. 18A, 18B, 19A, 19B, 20A, 20B,21A, and 21B are demonstrated with vertical rotational axes passingthrough each column, it is to be understood that the mixing devices inthe various mixing systems can be organized into rows, with each rowhaving a horizontal rotational axis passing through its center to rotateeach row horizontally rather than vertically.

The system may be controlled with a computer operated monitoring andfeedback control system. A properly configured control system couldmeasure peak load demands and open/close the mixing device array attimes lower pressure drop is needed (i.e., peak load in summer time whenusers are running the air conditioning units). The actuator operatingthis configuration also may be controlled by a properly configuredcontrol system with appropriately placed sensors.

FIG. 24 depicts a computer operated monitoring and feedback controlsystem 2400 according to an embodiment. The system 2400 includes a loadprofile meter 2404, other sensor(s) 2408, a sensor 2412 to determine adegree of rotation of a mixing device and/or mixing element relative toa gas flow direction, a set of mapping data structures 2416, a mixingdevice/element rotation system 2420, and a control system 2424.

The load profile meter 2404 determines when electricity (andcorresponding output at the power plant) is in high demand or peakconditions. This can be done using a load profile that plots variationin the electrical load versus time.

The other sensor(s) 2408 can be one or more sensors to determine one ormore of: the pressure drop of the mixing system, sorbent consumptionlevels, and/or sensed contaminant concentration in the gas stream priorto, during, or after treatment. For example, in a system utilizingactivated carbon for mercury control, the static mixing devices ormixing elements can be “closed” to create a higher pressure drop (andmore mixing) if sorbent consumption needs to be reduced. The same actioncould be taken if mercury emissions were running above target for agiven quantity of sorbent consumption (closing the mixing elements,increasing pressure drop, and increasing mixing), which would lowermercury emissions for the same quantity of sorbent.

The sensor to determine degree of rotation of the mixing device/mixingelement relative to gas flow direction can be any suitable sensor fordetermining angular displacement relative to a selected reference point.Any position sensor can be used that permits angular positionmeasurement. It can either be an absolute position sensor or a relativeone (displacement sensor). An example is a rotary encoder, also called ashaft encoder, which is an electro-mechanical device that converts theangular position or motion of a shaft or axle to an analog or digitalcode.

The mapping data structures 2416 are maintained in a computer readablemedium and can take many forms. In one form, the mapping data structuresare a two- or more dimensional lookup table that maps one or more sensedparameters, such as current power load, pressure drop, sorbentconsumption, and/or sensed contaminant concentration, against angularrotation or displacement of the mixing device and/or mixing elementsrelative to the direction of gas flow. A second mapping table can mapthe angular rotation or displacement to a command to the mixing deviceand/or element rotation system 2420 to cause the desired level ofangular displacement. As will be appreciated, the lookup table is anarray that replaces runtime computation with a simpler array indexingoperation. The indexing operation can be one or more of a simple lookupin an array, an associative array, or a linked list, a binary search inan array or an associative array, a trival hash function, and the like.The savings in terms of processing time can be significant, sinceretrieving a value from memory is often faster than undergoing anexpensive computation or input/output operation. Other forms of mappingdata structures can be employed depending on the application.Alternatively, the mapping data structures 2416 can be computationallydetermined in substantial real time, as in runtime computation.

The mixing device and/or element rotation system can be any actuatorsystem that effects angular displacement by one or more of mechanical,electromechanical, electromagnetic, magnetic, or hydraulicallyactuation.

The control system 2424 handles user input and output, supervises theoperation of the other system components, applies rules or policies, andissues commands to each of the components to effect desired operations.For example, the control system 2424, in response to determining, fromthe load profile meter, that the power plant and electrical output arein high demand or peak conditions high demand peak load condition orstate, can reduce the pressure drop.

The various components are in communication with one another via anetwork 2428, which can be a wired or wireless local area or wide areanetwork depending on the application.

FIG. 17 depicts the operation of the system 2400 according to anembodiment.

In step 1700, the control system 2424 detects a stimulus to change anorientation of a mixing device and/or mixing element. As noted, thestimulus can be one or more of current power load, pressure drop,sorbent consumption, and/or sensed contaminant concentration, againstangular rotation or displacement of the mixing device and/or mixingelements relative to the direction of gas flow.

In optional step 1704, the control system 2424 determines a currentpower load if not detected as a stimulus.

In step 1708, the control system 2424, using the mapping data structures2416, determines a desired maximum flow resistance and/or pressure dropacross the mixing device and/or elements.

In step 1712, the control system 2424 determines, from the mapping datastructures 2416, a degree of rotation of the mixing device and/orelements relative to a direction of gas flow to produce the desiredmaximum flow resistance and/or pressure drop. As noted, the pressuredrop is not simply bimodal, namely a maximum and minimum value. In someapplications, the mixing device and/or elements can be finely tuned toany one of various angular displacements to produce a desired pressuredrop while maintaining a desired degree of turbulent flow and mixing.For example, the angular orientation of the mixing device or elements isnot simply one of 0 or 90 degrees relative to a direction of gas flowbut can be any angle between those endpoints.

In step 1716, the control system 2424 generates and transmits, vianetwork 2828, a command to the rotation system 2420 to rotate the mixingdevice and/or elements to the desired degree of rotation or angulardisplacement relative to the direction of gas flow.

In optional step 1720, the control system 2424 measures the flowresistance or pressure drop by a sensor to confirm that the degree ofrotation and/or desired flow resistance result is correct.

The microprocessor in the control system then returns to step 1700.

A number of variations and modifications of the disclosure can be used.It would be possible to provide for some features of the disclosurewithout providing others.

For example, while ESP and baghouse particulate control devices arediscussed with reference to particulate removal, one or more other oralternative particulate and/or contaminant removal devices can beemployed as particulate control devices, such as wet and/or dryscrubbers.

The present disclosure, in various aspects, embodiments, andconfigurations, includes components, methods, processes, systems and/orapparatus substantially as depicted and described herein, includingvarious aspects, embodiments, configurations, subcombinations, andsubsets thereof. Those of skill in the art will understand how to makeand use the various aspects, aspects, embodiments, and configurations,after understanding the present disclosure. The present disclosure, invarious aspects, embodiments, and configurations, includes providingdevices and processes in the absence of items not depicted and/ordescribed herein or in various aspects, embodiments, and configurationshereof, including in the absence of such items as may have been used inprevious devices or processes, e.g., for improving performance,achieving ease and\or reducing cost of implementation.

The foregoing discussion of the disclosure has been presented forpurposes of illustration and description. The foregoing is not intendedto limit the disclosure to the form or forms disclosed herein. In theforegoing Detailed Description for example, various features of thedisclosure are grouped together in one or more, aspects, embodiments,and configurations for the purpose of streamlining the disclosure. Thefeatures of the aspects, embodiments, and configurations of thedisclosure may be combined in alternate aspects, embodiments, andconfigurations other than those discussed above. This method ofdisclosure is not to be interpreted as reflecting an intention that theclaimed disclosure requires more features than are expressly recited ineach claim. Rather, as the following claims reflect, inventive aspectslie in less than all features of a single foregoing disclosed aspects,embodiments, and configurations. Thus, the following claims are herebyincorporated into this Detailed Description, with each claim standing onits own as a separate preferred embodiment of the disclosure.

Moreover, though the description of the disclosure has includeddescription of one or more aspects, embodiments, or configurations andcertain variations and modifications, other variations, combinations,and modifications are within the scope of the disclosure, e.g., as maybe within the skill and knowledge of those in the art, afterunderstanding the present disclosure. It is intended to obtain rightswhich include alternative aspects, embodiments, and configurations tothe extent permitted, including alternate, interchangeable and/orequivalent structures, functions, ranges or steps to those claimed,whether or not such alternate, interchangeable and/or equivalentstructures, functions, ranges or steps are disclosed herein, and withoutintending to publicly dedicate any patentable subject matter.

We claim:
 1. A contaminated gas treatment system, comprising: a thermalunit to produce a contaminated gas stream comprising a contaminant; anair heater positioned in a flow path of the contaminated gas streamdownstream from the thermal unit to transfer thermal energy from thecontaminated gas stream to air prior to introduction of the air into thethermal unit; an in-line mixing device positioned in the flow path ofthe contaminated gas stream downstream from the thermal unit to induceturbulent flow in the contaminated gas stream, the in-line mixing devicebeing positioned in a duct defining the flow path of the contaminatedgas stream, wherein the in-line mixing device comprises a static mixingdevice, wherein the static in-line mixing device comprises one or morestationary mixing elements fixed in a housing of the mixing device,wherein the static in-line mixing device rotates relative to a flowdirection of the contaminated gas stream, wherein, when the staticin-line mixing device is in a first position relative to the flowdirection, the contaminated gas stream has a first pressure drop overthe in-line mixing device, wherein, when the static in-line mixingdevice is in a different second position relative to the flow direction,the contaminated gas stream has a second pressure drop over the in-linemixing device, wherein the first and second pressure drops aredifferent, and wherein at least one of the following is true: (a) awidth of the in-line mixing device is no more than about 75% of a widthof the duct at the position of the in-line mixing device; (b) a heightof the in-line mixing device is no more than about 75% of a height ofthe duct at the position of the in-line mixing device; and (c) across-sectional area of the in-line mixing device normal to a directionof gas flow is no more than about 75% of a cross-sectional area of theduct at the position of the in-line mixing device; and an additiveinjection system positioned in the flow path of the contaminated gasstream upstream or downstream of the in-line mixing device to introducean additive into the contaminated gas stream, the additive controlling acontaminate level in a treated gas stream prior to discharge of thetreated gas stream into the environment, wherein the in-line mixingdevice and additive injection system cause the additive-containing gasstream to comprise a substantially homogeneous distribution of theadditive in the additive-containing gas stream; and a particulatecontrol device positioned in the flow path of the contaminated gasstream downstream of the in-line mixing device to remove particulatesfrom the additive-containing gas stream and form the treated gas stream;a computer; a rotation sensor to determine a degree of angular rotationof the in-line mixing device and/or a mixing element of the mixingdevice relative to the flow direction; one or more gas stream sensors todetermine one or more sensed parameters comprising one or more of thepressure drop over the in-line mixing device, an additive consumptionlevel, and a contaminant concentration in the gas stream prior to orafter additive injection; a rotation system to rotate the in-line mixingdevice and/or mixing element; and a computer operated control system incommunication with the rotation sensor, one or more gas stream sensors,and rotation system and comprising a set of mapping data structuresmapping one or more sensed parameters against a degree of angularrotation of the mixing device and/or mixing element and instructionsthat, when executed by the computer, cause the computer operated controlsystem to: receive a degree of current angular rotation of the in-linemixing device and/or mixing element and the one or more sensedparameters; based on the received degree of current angular rotation ofthe in-line mixing device and/or mixing element and the one or moresensed parameters, determine, from the mapping data structures, a newdegree of angular rotation of the in-line mixing device and/or mixingelement; and cause the in-line mixing device and/or mixing element torotate from the current angular rotation to the new angular rotation. 2.The system of claim 1, wherein the thermal unit combusts thecontaminated feed material to produce the contaminated gas stream andwherein (a) is true.
 3. The system of claim 2, wherein the width of thein-line mixing device is no more than about 50% of the duct width at thein-line mixing device position.
 4. The system of claim 1, wherein thethermal unit combusts the contaminated feed material to produce thecontaminated gas stream and wherein (b) is true.
 5. The system of claim4, wherein the height of the in-line mixing device is no more than about50% of the duct height at the in-line mixing device position.
 6. Thesystem of claim 1, wherein the thermal unit combusts the contaminatedfeed material to produce the contaminated gas stream and wherein (c) istrue.
 7. The system of claim 6, wherein the in-line static mixing devicehas a cross-sectional area of the in-line mixing device normal to adirection of gas flow that is no more than about 50% of across-sectional area of the duct at the position of the in-line mixingdevice.
 8. The system of claim 7, wherein the in-line mixing devicecomprises a plurality of mixing elements to induce turbulence of thecontaminated gas stream, wherein the in-line static mixing device has across-sectional area of the in-line mixing device normal to a directionof gas flow that is no more than about 25% of a cross-sectional area ofthe duct at the position of the in-line mixing device and wherein aremainder of the cross-sectional area of the duct at the position of thein-line mixing device is free of any mixing elements.
 9. The system ofclaim 1, wherein a distance from an output of the in-line mixing deviceto an input of the particulate control device is at least about onetimes but no more than about ten times a hydraulic diameter of the duct,and wherein the additive is injected upstream and/or downstream of thein-line mixing device.
 10. The system of claim 1, wherein the additiveinjection system is positioned upstream of the in-line mixing device,wherein a distance from an input of the in-line mixing device to anoutput of the additive injection system is at least about 0.1 times butno more than about one times a hydraulic diameter of the duct, whereinthe additive is a liquid additive, and wherein the additive is injecteddownstream of, and in the turbulent contaminated gas stream flowproduced by, the in-line mixing device.
 11. A contaminated gas treatmentsystem, comprising: an in-line mixing device positioned in a flow pathof a contaminated gas stream, comprising a contaminant, downstream froma thermal unit to induce turbulent flow in the contaminated gas stream,the in-line mixing device being positioned in a duct defining the flowpath of the contaminated gas stream, wherein the in-line mixing devicecomprises a static mixing device, wherein the static in-line mixingdevice comprises one or more stationary mixing elements fixed in ahousing of the in-line mixing device, wherein the static in-line mixingdevice rotates relative to a flow direction of the contaminated gasstream, wherein, when the in-line mixing device is in a firstorientation relative to the flow direction, the contaminated gas streamhas a first pressure drop over the in-line mixing device, wherein, whenthe in-line mixing device is in a different second orientation relativeto the flow direction, the contaminated gas stream has a second pressuredrop over the in-line mixing device, wherein the first and secondpressure drops are different, and wherein at least one of the followingis true: (a) a width of the in-line mixing device is no more than about75% of a width of the duct at the position of the in-line mixing device;(b) a height of the in-line mixing device is no more than about 75% of aheight of the duct at the position of the in-line mixing device; and (c)a cross-sectional area of the in-line mixing device normal to adirection of gas flow is no more than about 75% of a cross-sectionalarea of the duct at the position of the in-line mixing device; and anadditive injection system positioned in the flow path of thecontaminated gas stream upstream or downstream of the in-line mixingdevice to introduce an additive into the contaminated gas stream, theadditive controlling a contaminate level in a treated gas stream priorto discharge of the treated gas stream into the environment, wherein thein-line mixing device and additive injection system cause theadditive-containing gas stream to comprise a substantially homogeneousdistribution of the additive in the additive-containing gas stream; anda particulate control device positioned in the flow path of thecontaminated gas stream downstream of the in-line mixing device toremove particulates from the additive-containing gas stream and form thetreated gas stream; a computer; a rotation sensor to determine a degreeof angular rotation of the mixing device and/or a mixing element of thein-line mixing device relative to the flow direction; one or more gasstream sensors to determine one or more sensed parameters comprising oneor more of the pressure drop, an additive consumption level, and acontaminant concentration in the gas stream prior to or after sorbentinjection; a rotation system to rotate the in-line mixing device and/ormixing element; and a computer operated control system in communicationwith the rotation sensor, one or more gas stream sensors, and rotationsystem and comprising a set of mapping data structures mapping one ormore sensed parameters against a degree of angular rotation of themixing device and/or mixing element and instructions that, when executedby the computer, cause the computer operated control system to: receivea degree of current angular rotation of the mixing device and/or mixingelement and the one or more sensed parameters; based on the receiveddegree of current angular rotation of the mixing device and/or mixingelement and the one or more sensed parameters, determine, from themapping data structures, a new degree of angular rotation of the in-linemixing device and/or mixing element; and cause the in-line mixing deviceand/or mixing element to rotate from the current angular rotation to thenew angular rotation.
 12. The system of claim 11, wherein a thermal unitcombusts a contaminated feed material to produce the contaminated gasstream and wherein (a) is true.
 13. The system of claim 12, wherein thecontaminated gas stream has a gas velocity ranging from about 5 to about50 m/s, and wherein the width of the in-line mixing device is no morethan about 50% of the duct width at the in-line mixing device position.14. The system of claim 11, wherein a thermal unit combusts acontaminated feed material to produce the contaminated gas stream andwherein (b) is true.
 15. The system of claim 14, wherein the height ofthe in-line mixing device is no more than about 50% of the duct heightat the in-line mixing device position.
 16. The system of claim 11,wherein a thermal unit combusts a contaminated feed material to producethe contaminated gas stream and wherein (c) is true.
 17. The system ofclaim 16, wherein the in-line static mixing device has a cross-sectionalarea of the in-line mixing device normal to a direction of gas flow thatis no more than about 50% of a cross-sectional area of the duct at theposition of the in-line mixing device, and wherein the in-line mixingdevice comprises a plurality of mixing elements to induce turbulence ofthe contaminated gas stream.
 18. The system of claim 17, wherein theplurality of mixing elements are stationary, fixed, and/or staticfan-type blades, wherein the in-line static mixing device has across-sectional area of the in-line mixing device normal to a directionof gas flow that is no more than about 25% of a cross-sectional area ofthe duct at the position of the in-line mixing device and wherein aremainder of the cross-sectional area of the duct at the position of thein-line mixing device is free of any mixing elements.
 19. The system ofclaim 11, wherein the additive is injected upstream and/or downstream ofthe in-line mixing device.
 20. The system of claim 11, wherein theadditive injection system is positioned downstream of the in-line mixingdevice, wherein the additive is a liquid additive, and wherein theadditive is injected downstream of, and in the turbulent contaminatedgas stream flow produced by, the in-line mixing device.
 21. The systemof claim 1, wherein the thermal unit causes generation of electricalpower, wherein the one or more gas stream sensors determines thepressure drop over the in-line mixing device, wherein the computeroperated control system is in communication with a load profile meterthat determines a current demand for electrical power, and wherein thecomputer operated control system, based on a current electrical powerdemand, selects a pressure drop over the mixing device, and uses thepressure drop to select the new degree of angular rotation.
 22. Thesystem of claim 11, wherein the thermal unit causes generation ofelectrical power, wherein the one or more gas stream sensors determinesthe pressure drop, wherein the computer operated control system is incommunication with a load profile meter that determines a current demandfor electrical power, and wherein the computer operated control system,based on a current electrical power demand, selects a pressure drop overthe mixing device, and uses the pressure drop to select the new degreeof angular rotation.
 23. A contaminated gas treatment system,comprising: an in-line mixing device positioned in a flow path of acontaminated gas stream, comprising a contaminant, downstream from athermal unit to induce turbulent flow in the contaminated gas stream,the in-line mixing device being positioned in a duct defining the flowpath of the contaminated gas stream, wherein the in-line mixing deviceis positioned in only a first portion of a cross-sectional area of theduct normal to a direction of gas flow and a second portion of thecross-sectional area of the duct is free of the in-line mixing device,wherein the in-line mixing device comprises a static mixing device,wherein the static in-line mixing device comprises one or morestationary mixing elements fixed in a housing of the in-line mixingdevice, wherein the static in-line mixing device rotates relative to aflow direction of the contaminated gas stream, wherein, when the in-linemixing device is in a first position relative to the flow direction, thecontaminated gas stream has a first pressure drop over the in-linemixing device, wherein, when the in-line mixing device is in a differentsecond position relative to the flow direction, the contaminated gasstream has a second pressure drop over the in-line mixing device, andwherein the first and second pressure drops are different, and whereinthe first portion of the cross-sectional area is no more than about 75%of a cross-sectional area of the duct at the position of the in-linemixing device; an additive injection system positioned in the flow pathof the contaminated gas stream upstream or downstream of the in-linemixing device to introduce an additive into the contaminated gas stream,the additive controlling a contaminate level in a treated gas streamprior to discharge of the treated gas stream into the environment,wherein the in-line mixing device and additive injection system causethe additive-containing gas stream to comprise a substantiallyhomogeneous distribution of the additive in the additive-containing gasstream; a particulate control device positioned in the flow path of thecontaminated gas stream downstream of the in-line mixing device toremove particulates from the additive-containing gas stream and form thetreated gas stream; a computer; a rotation sensor to determine a degreeof angular rotation of the mixing device and/or a mixing element of themixing device relative to the flow direction; one or more gas streamsensors to determine one or more sensed parameters comprising one ormore of the pressure drop over the in-line mixing device, an additiveconsumption level, and a contaminant concentration in the gas streamprior to or after additive injection; a rotation system to rotate themixing device and/or mixing element; and a computer operated controlsystem in communication with the rotation sensor, one or more gas streamsensors, and rotation system and comprising a set of mapping datastructures mapping one or more sensed parameters against a degree ofangular rotation of the mixing device and/or mixing element andinstructions that, when executed by the computer, cause the computeroperated control system to: receive a degree of current angular rotationof the in-line mixing device and/or mixing element and the one or moresensed parameters; based on the received degree of current angularrotation of the in-line mixing device and/or mixing element and the oneor more sensed parameters, determine, from the mapping data structures,a new degree of angular rotation of the in-line mixing device and/ormixing element; and cause the in-line mixing device and/or mixingelement to rotate from the current angular rotation to the new angularrotation.
 24. The system of claim 23, wherein the thermal unit causesgeneration of electrical power, wherein the one or more gas streamsensors determines the pressure drop over the in-line mixing device,wherein the computer operated control system is in communication with aload profile meter that determines a current demand for electricalpower, and wherein the computer operated control system, based on acurrent electrical power demand, selects a pressure drop over thein-line mixing device, and uses the pressure drop to select the newdegree of angular rotation.